WO1982000174A1

WO1982000174A1 - Method of operating an internal combustion engine with turbocharge system,and internal combustion engine with turbocharge system for use in carrying out the method

Info

Publication number: WO1982000174A1
Application number: PCT/DK1981/000068
Authority: WO
Inventors: A Ostergaard
Original assignee: A Ostergaard
Priority date: 1980-07-04
Filing date: 1981-07-03
Publication date: 1982-01-21
Also published as: FI70452B; DK155452B; FI820587L; DK290280A; DK155452C; EP0058678A1; JPH02291423A; FI70452C; JPS57500941A; NO820635L; EP0058678B1

Abstract

The method serves to establish an energy reserve that can be used for levelling out variations of the manner of operation of the engine. To this end, a fraction only of the exhaust gas delivered by the engine (1) under the conditions of operation existing at normal temperatures in temperate geographical areas is passed to the turbocharge system (5) while the remaining fraction of the exhaust gas delivered by the engine is caused to by-pass the turbocharge system (5). By reducing the by-passed fraction, a full or partial compensation is obtained for the reduction of the charging of the cylinders which would otherwise occur in the case of an increase of the temperature of the air taken in by the turbocharge system (5). A compensation may also be made for dropping efficiency of the turbocharge system, viz. by reducing the fraction of the exhaust gas by-passing the turbocharge system (5). The internal combustion engine (1) with the turbocharge system (5) has means (9) for branching-off a fraction of the exhaust gas from the engine so as to conduct this fraction in by-pass to the turbocharge system (5) and either to the atmosphere or to a boiler (70), if desired through an apparatus for the utilization of secondary energy. The branch-off means (9) are adjusted towards reduction of the passage area when the temperature of the intake air rises, and when the efficiency of the turbocharge system (5) drops.

Description

Method of operating an internal combustion engine with turbocharge system , and internal combustion engine with turbocharge system for use in carrying out the method .

The invention relates to a method of operating an internal combustion engine with turbocharge system. By turbocharge system is to be understood herein one or more turbine operated compressors which feed scavenging-/charging air to the cylinder or cylinders of the engine, normally through one or more air coolers.

It is usage in the trade that an internal combustion engine with turbocharge system, when delivered , is adjusted as favourably as possible in relation to the climatic and environmental conditions existing at the time and place in question . In the case of an internal combustion engine with turbocharge system for use as a marine engine, the turbocharge system is so dimensioned and adjusted at delivery with fixed adjustments in such a manner that the appurtenant internal combustion engine exhibits optimum operation at the testbed trial in the workshop at the time of delivery, i . e. in such a manner that the engine renders the best possible results so as to fulfil the prescribed conditions in respect of maximum performance and the specific fuel consumption within the prescribed and constructional ly contemplated engine control limits and under particularly favourable conditions . The present invention is based on the recognition that an engine with turbocharge system, which is dimensioned, adjusted , and fixed in its adjustment of the turbocharge system in the manner described , will not in the later operation , frequently under particularly adverse conditions, on an average yield a maximum of energy at a minimum of fuel consumption and at the lowest possible thermal load . Considering e. g . a marine engine, which is delivered in a temperate climate, the turbocharge system is adjusted to have a turbine area such that at the intake temperature and other climatic conditions, such as the barometric level , and special conditons of installation existing at the location in question , the turbocharge system will yield the highest possible amount of scavenging-/charging air so as to achieve the best possible svavenging and the prescribed charging pressure, and thereby the engine will in the best possible way fulfil the prescribed conditions at low temperatures of the parts of the engine. If, however, the ambient conditions are changed in an adverse direction , e. g . if the ship in question sails in tropic waters, the temperature of the air intake of the turbocharger will rise in relation to that normally prevailing at delivery, and at the same time the barometric level may be low, so that the engine operates under conditions less favourable than at delivery. A higher intake temperature increases the compressional work per weight unit of air, and this is not made up for by a correspondingly increased energy from the turbine portion of the turbocharge system. Consequently, the amount of air input to the engine is reduced, and the same will happen at low barometric level . This again means that the quantity by weight of air supplied to the cylinders of the engine is reduced . From the recognition of these circumstances it is the object of the present invention to provide a method by which an improved economy of the internal combustion engine with its turbocharge system can be obtained , especially under such adverse conditions. To achieve this, according to the invention , a turbocharge system and an engine are used which are so constructed and dimensioned, and the turbocharge system has an efficiency so high, that at low air intake temperature the turbocharge system is capable of delivering the amount of air calculated or suitable for the engine at the pressure calculated or suitable far the engine when a fraction only of the exhaust gas delivered by the engine is fed to the turbocharge system, and this turbocharge systefn and engine are run in such a manner that, at low air intake temperature a fraction only of the exhaust gas delivered by the engine is fed to the turbocharge system, the remainder of the exhaust gas being conducted to the atmosphere in by-pass to the turbocharge system, the proportion between the fraction of the exhaust gas by-passing the turbocharge system and the fraction of the exhaust gas supplied to the turbocharge system being decreased at Increasing air intake temperature and increased at decreasing air intake temperature. Hereby the advantage is obtained that under favourable conditions of operation , e. g . under temperate climatic conditions with periodic low temperatures, a reserve of energy is in readiness for the turbocharge system so that, in case the engine has to operate under warmer conditions than those prevailing at the time of delivery, the turbocharge system can be caused to supply a relatively increased amount of scavenging-/charging air to the engine, the turbocharge system receiving in these changed circumstances an increased amount of the exhaust gas delivered by the engine, viz. by decreasing the proportion between the fraction of the exhaust gas by-passing the turbocharge system and the fraction of the exhaust gas supplied to the turbocharge system . Thereby the conditions of operation of the engine are improved in otherwise adverse circumstances, viz. partly by reduction of the thermal load and partly by reduction of the fuel consumption , and the present invention is based on the recognition that an improvement of economy is thereby obtained , which is considerably greater than the small loss of economy that may be involved by the method when the engine operates in favourable circumstances with cold intake air. Similarly, viz. by reducing the said proportion, a compensation can be made for drop of the barometric level . Thus, the adjustment of the engine is advantageously controlled in time with fluctuating temperature conditions, and preferably also in time with fluctuating barometric level . Moreover, when an engine with a turbocharge system is delivered, the turbocharge system will operate at its maximum, i . e. at its highest efficiency. Experience has shown, however, that the effi ciency of a turbocharge system decreases gradually in the course of time, viz. primarily as a consequence of smudging . This occurrence, too, can be compensated for by the method according to the invention , viz. by reducing the said proportion so as to supply a relatively increased amount of exhaust gas to the turbocharge system and thereby to compensate for the dropping efficiency of the turbocharge system. On account of the smudging of the turbocharge system explained above, an overhaul of the turbocharge system is performed at suitable time intervals, whereby the efficiency of the turbocharge system again increases. The method according to the present invention also involves the possibility of compensating for the improved efficiency of the turbocharge system obtained after such an overhaul , viz. if the proportion between the fraction of the exhaust gas by-passed to the atmosphere and the fraction supplied .to the turbocharge system is increased after overhaul of the turbocharge system. Thereby the turbocharge system can be fed with the exact amount of exhaust gas corresponding to the demand of the turbocharger after such an overhaul . Hereby a compensation is obtained for a further factor giving rise to fluctuations in respect of the working conditions, thermal load and fuel consumption of the engine, and which would reduce the average degree of utilization of the engine.

According to experience, it is a fact that at the time of delivery, where everything is new, the efficiency of the turbocharge system has its maximum value which will never again be reached by later overhauls in normal operation . This, together with other advan tages during a test run in a workshop, means that the supply of air from the turbocharge system to the engine takes place under so favourable conditions that this is not achieved later during operation of the engine as finally installed . In other words, an initial drop of efficiency of the turbocharge system is to be anticipated . In recognition of this fact, a manner of carrying out the method is proposed which is characterized in that the proportion between the fraction of the exhaust gas by-passed to the atmosphere and the proportion supplied to the turbocharge system is decreased by a predetermined limited amount during the progress of a certain time interval after the taking into use of the engine to compensate for the abatement of the air delivery conditions of the turbocharge system and its initial drop of efficiency. This manner of carrying out the method permits of a simplification of the control system and a reduction of the control range which must additionally be available for carrying out the method to make up for the daily, yearly and geographically determined temperature fluctuations and the periodically varying reductions of efficiency of the turbocharge system between overhauls , as well as the variations of load. The method according to the invention also has the inherent advantage that the fraction of the exhaust gas by-passed to the atmosphere may, before expanding into the atmosphere, be utilized for the production of energy, in the following referred to as secondary energy. Such utilization is therefore effected in a manner of carrying out the method . Such a utilization is particularly advantageous because under temperate or cold conditions a high amount of by-passed exhaust gas will be available for such secondary energy production , and exactly under such conditions there will be a great demand for such a production of secondary energy, e. g. for the operation of generators for supplying illumination or other forms of auxiliary energy. After the by-passed fraction of the exhaust gas has been used for the production of secondary energy, it may still contain thermal energy, and this may have substantially the same unitary value as the fraction of the exhaust gas that has passed through the turbocharge system, and may be conducted together with the latter to the atmosphere, either directly or through an apparatus for the utilization of the thermal energy content of the gas, e. g . through a heat exchanger in the form of an exhaust gas boiler where the thermal energy of the exhaust gas is utilized e.g. for the production of steam for heating or for the operation of steam turbines delivering mechanical energy. Alternatively, the by-passed fraction of the exhaust gas may be conducted directly to such an apparatus without first having been used for secondary energy production . Thus, there are four cases in respect of the conduction of the exhaust gas in by-pass to the turbocharge system and to the atmosphere, viz. :

1 . directly to the atmosphere without secondary energy production and without utilization of thermal energy, 2. delivery to the atmosphere after secondary energy production and without utilization of thermal energy,

3. delivery to the atmosphere without secondary energy production, but after utilization of thermal energy,

4. delivery to the atmosphere after secondary energy pro duction and after utilization of thermal energy.

From the point of view of economy of operation, the optimum utilization of the engine with turbocharge system according to the invention will in the four cases be achieved by decreasing the by-passed amount of exhaust gas at increasing intake temperature, and for the individual cases mentioned by an increasing by-pass amount from case 1 ) with the lowest by-pass amount and to case 4) with the highest by-pass amount.

The cases can be subdivided into two which from the point of view of control differ in principle on some points , viz. A. Without utilization of the energy of the exhaust gas (case 1 )) , and B . With utilization of the energy of the exhaust gas (cases

2) , 3), and 4)) . I n case A the control is performed solely with a view to the economy of the engine as such , i . e. its specific oil consumption and its mechanical and thermal stresses, which means that the by-pass amount is normally decreased at decreasing engine output. Hereby it becomes possible at relatively low output values to keep the scavenging pressure and the charging pressure, and thereby the maximum pressure, as close as possible to the designed value, so that the spare energy can be used for a particularly strong reduction of the thermal load of the engine and for lowering the fuel consumption . In case B the control also involves consideration for the utilization of the energy of the by-passed exhaust gas as indicated in the cases 2) , 3) and 4) , which means that in order to achieve optimum economy of operation, the control , besides generally going towards an increase of the by-pass amount also in relation to case 1 ) , should go towards an increase of the by-pass amount at a lowering of the output in the range from 100% to e. g . 70%, especially in case 4) where there should still be a sufficient total production of energy from the exhaust gas to meet the heat and electricity needs in daily voyage at sea, without the increased by-pass amount resulting in mechanical or thermal stresses exceeding the stresses at 100 or the values for which the engine is designed . As will be apparent from that mentioned above, the variation of the fraction of the exhaust gas caused to by-pass the turbocharge system is effective for mitigating adverse effects resulting partly from fluctuations of climatic conditions, and partly from gradual changes of the overall efficiency of the turbocharge system, and is also effective for meeting varying needs of energy production from the exhaust gas.

The invention also relates to an internal combustion engine with turbocharge system for use in carrying out the method . According to the invention, this internal combustion engine with turbocharge system is characterized in that the turbocharge system and the engine are so constructed and dimensioned , and the turbocharge system has an efficiency so high , that at low air intake temperature the turbocharge system is capable of delivering the amount of air calculated or suitable for the engine at the pressure calculated or suitable for the engine when a fraction only of the exhaust gas delivered by the engine is fed to the turbocharge system through appurtenant feeding means, and the engine has means for branching off the remaining fraction of the exhaust gas delivered by the engine so that this fraction is passed to the atmosphere in by-pass to the turbocharge system, the engine being provided with control means which are so arranged and actuable in such a manner that the proportion between the fraction of the exhaust gas caused to by-pass the turbocharge system through the branch-off means and the fraction of the exhaust gases supplied to the turbocharge system through the feeding means is adapted to be decreased at increasing air intake temperature and to be increased at decreasing air intake temperature.

In carrying out this arrangement, the said proportion may be controlled by means of control means arranged in the branch-off means, in the feeding means or both in the branch-off means and in the feeding means, but preferably, according to the invention , the control means are arranged to control the passage area of the branch- off means, thereby to avoid throttling in the feeding means which feed the exhaust gases to the turbocharge system . The control means are preferably actuable in such a manner that the passage area of the branch-off means is decreased in the case of drop of the efficiency of the turbocharge system, whereby the maximum extent of the above mentioned variation of the branched-off amount of gas is correspondingly limited. In this connection the con trol means may, according to the invention , comprise means for permanently decreasing the maximum passage area of the branch-off means by an amount corresponding to the drop of the initial efficiency of the turbocharge system not regenerated later, and to the drop of air input normally taking place owing to changes of installation conditions from test run in the workshop to the final operation of the completed system. The said means may advantageously, according to the invention , be constituted by a separate throttle which is closed after a few months of operation and is not utilized later. The closing of the throttle may take place gradually within a few months of operation . In the case where the fraction of the exhaust gas by-passed to the atmosphere is not utilized for the production of secondary energy, the control means may advantageously, according to the invention , be adapted to decrease the passage area of the branch-off means at decreasing engine load, and to increase the passage area of the branch-off means at increasing engine load .

I n the case where the branch-off means are arranged to supply the branched-off fraction of the exhaust gas to an apparatus for the production of secondary energy, the control means may advantageously be arranged to increase the passage area of the branch-off means at increasing demand for secondary energy utilization and to decrease the passage area of the branch-off means at decreasing demand for secondary energy.

I n the case where the branch-off means are arranged to supply the branched-off fraction of the exhaust gas to an apparatus for utilizing the energy content of the exhaust gas , the control means of the branch-off means may advantageously be arranged to control in a direction towards increase of the passage area of the branch-off means at oropping engine load down to the limit imposed by the consideration for the thermal load or specific consumption of the engine or where the energy of the gas can only cover a relatively small fraction of the demand, or is of insignificant value as seen in relation to the complications involved by continuing the operation of the apparatus in question. Below that engine load the branch-off means are closed completely or to the extent compatible with the consideration for the stability of the turbocharge system.

The invention will now be further explained with reference to the drawing, in which

Fig. 1 diagrammatically shows a first embodiment of the in ternai combustion engine with turbocharge system according to the invention, Fig. 2 diagrammatically a control system for the engine shown in Fig. 1 , Fig. 3 a second embodiment of the internal combustion engi ne with turbocharge system according to the invention, in end view, Fig. 4 the same in top view, but with some parts omitted , Fig . 5 diagrammatically a control system for the engine shown in Figs. 3 and 4, Fig. 6 diagrammatically a gas turbine for utilization of the energy in a fraction of the exhaust gas delivered by the engine of Figs. 3 and 4, and Fig . 7 a section through the gas turbine of Fig . 6 with appurtenant generator. in the drawing, 1 is an engine in the form of a diesel engine. The exhaust pipe system of the engine is diagrammatically shown at 2 and this is connected with a receiver 3 for exhaust gas . The receiver is connected via feeding means, diagrammatically illustrated as a passage 4, with a turbocharge system 5, likewise diagrammatically illustrated, the pressure side of which feeds a receiver 6 via an air cooler 7, from which the engine is provided with scavenging and charging air. In the embodiment shown in Fig. 1 , the engine is provided with a diagrammatically illustrated steam boiler 70 for utilizing the thermal energy in the exhaust gas . The boiler 70 has a pipe stub 71 for the supply of water and a pipe stub 72 for delivering steam . The boiler is connected with the exhaust gas receiver 3 by means of branch-off means, diagrammatically illustrated in the form of a passage 11 , in which control means are provided, diagrammatically illustrated in the form of a control throttle 9. Moreover, the boiler is connected through a passage 73 to the exhaust side of the turbine portion 8 of the turbocharge system. The two passages 11 and 73 are connected to a common inlet 74 to the boiler 70, but they may by means of a throttle 75 be connected with an exhaust conduit 76 leading directly to the atmosphere.

By means of the passage 11 and the throttle 9 a greater or smaller fraction of the exhaust gas, which would otherwise be supplied to the turbocharge system 5 through the passage 4, may, depending on the position of the throttle 9, be conducted in by-pass to the tur bocharge system and directly to the boiler 70 through the passage 74, or directly to the atmosphere through the exhaust conduit 76. It will be understood that if it is not desired to utilize the thermal energy by means of a boiler or other form of energy converter or heat exchanger, the passage 11 and the passage 73 open directly into the atmos phere.

The turbocharge system 5 and the engine 1 are so constructed and dimensioned, and the turbocharge system has an efficiency so high , that under temperate conditions the turbocharge system will yield the air necessary for scavenging and charging the cylinders of the engine 1 , even if a certain amount of exhaust gas is conducted in by-pass to the turbocharge system 5 by means of the passage 11 and the throttle 9.

Fig . 2 shows diagrammatically how the engine 1 and its turbocharge system 5 of Fig . 1 are controlled under varying conditions. Fig . 2 shows again the diagrammatically represented throttle 9 which is rotatably mounted on a shaft 10 in the interior of the passage 11 . As shown in Fig . 2, the throttle 9 is connected with a lever system consisting of three levers 14, 15 and 16, each of which is mounted for rotation about a shaft 17, 18 and 19, respectively belonging thereto. This control system is to be understood as purely symbolic and is only intended to illustrate one way in which such a control system may be constructed . The shaft 19 of the lowermost lever 16 is fixedly supported relatively to a part of the engine or the turbocharge system by means of a support 20, and one arm 21 of the lever 16 is connected through a rod 22 with the shaft 18 of the lever 15, and one arm 23 of the lever 15 is connected through a rod 24 with the shaft 17 of the lever 14. One arm 25 of the lever 14 is connected through a rod connection 26 with the throttle 9. Each of the rods 22 and 24 is guided in a vertical direction by means of a sliding guide diagrammatically indicated at 28 and 29, respectively.

The second arm 30 of the lever 14 is connected in a manner not illustrated with a sensor which senses the temperature of the intake air of the turbocharge system 5 and which at increasing intake temperature, possibly in combination with dropping barometric level, moves the arm 30 in the direction of the arrow 31 . Thereby the throttle 19 is moved in the closing direction , which again means that a smaller amount of exhaust gas is branched-off, or in other words a higher amount of exhaust gas flows to the turbocharge system 5. Thereby a compensation is made for the increasing intake temperature, a greater quantity by weight of air being supplied to the receiver 6 from the compressor portion of the turbocharge system 5.

The second arm 32 of the lever 15 is connected in a manner not illustrated with an instrument governed by the load of the engine. This end 32 of the lever 15 may e. g . be moved from the load and control handle of the engine, and it is moved in the direction of the arrow 33 at increasing load of the engine. Thereby the rod 24 and consequently the shaft 17 are moved downwards, and consequently the throttle 10 is moved in a direction towards increase of the branch-off amount. In other words, the gas supply to the turbocharge system is decreased and thereby the scavenging and charging of the engine are reduced so that the scavenging and charging pressure can be kept as close to and , if necessary, exactly on the design value.

The second arm 34 of the lever 21 is moved in dependence on the efficiency of the turbocharger 5. The efficiency and air output of a turbocharger drop from the time of delivery of the engine in question, i. e. the time when the engine is subjected to its final test run and is delivered . Experience shows that the good efficiency and air output which the turbocharge system exhibits at the final test run cannot be obtained later unless the turbocharge system is completely renovated . Thus, there will always be an initial drop of the efficiency and air output after the taking into use of the turbocharge system, and moreover the efficiency and air output of the turbocharge system drop in the later operation , particularly owing to smudging . The latter may be remedied by performing an overhaul of the turbocharge system. At a drop of the efficiency of the turbocharge system the arm 34 is moved opposite to the direction of the arrow 35, whereby the rod 22 and thereby the shaft 18 are lifted , which again results in lifting of the rod 24 and the shaft 17 so that in other words the throttle 9 is moved in the closing direction . Now a smaller amount of gas is branched off, and the turbocharge system is provided with the extra amount of gas necessary for compensating for the dropping efficiency and air output of the turbocharger. Upon overhaul of the turbocharge system, which is performed at predetermined time intervals viz. when smudging becomes excessive, the arm 34 is moved in the direction of the arrow 35, whereby the throttle 9 is moved in the opening direction . Owing to the initial drop of the efficiency and the air output explained above it will be understood that upon an overhaul a smaller amount of gas is to be branched off than was the case at the time of taking into use of the turbocharge system, and consequently the throttle 9 shouid be closed beyond the position it occupied at the time of taking into use in order that the resulting increase of the amount of gas supplied to the turbocharge system may compensate for the initial drop . This can be done by connecting the lever 16 with means , not shown , for shifting its control range in such a manner that after the initial drop and an overhaul of the turbocharge system have taken place, the lever 16 regulates the position of the throttle between a more closed and a less opόn position than was the case in the time interval between the taking into use and the first overhaul . Seeing that, in other words, once the initial drop has occurred, the control is to be performed as if the passage 11 had a smaller area than before the initial drop occurred, it is possible, instead of shifting the control range of the lever 16, to use another solution , which is shown in Fig . 1 and consists in the provision of a shunt conduit 78 which connects the receiver 3 or the passage 11 upstream of the throttle 9 with the passage 74, and which contains a throttle 79. During the time when the initial drop takes place the throttle 79 is open so that the amount of gas not required for the turbocharge system during the period of maximum efficiency and air output is passed either to the boiler 70 or to the atmosphere, depending on the position of the throttle 75. When the initial drop has taken place, the throttle 79 is closed , and the correspondingly increased amount of gas is supplied to the turbocharge system 5 through the passage 4, thereby to compensate for the initial drop . Owing to this arrangement, the lever 16 need only have a control range corresponding to the variation of the efficiency and air output of the turbocharge system occurring between the overhauls.

In the embodiment of the engine with turbocharge system according to the invention illustrated in Figs. 3 and 4, the reference characters used are on the whole the same as in Fig . 1 , 1 referring to the engine as such, 2 the exhaust sytem of the engine, 3 a receiver which receives the exhaust gas from the cylinders, and 4 diagrammatically representing feeding means illustrated in the form of a passage for supplying exhaust gas from the receiver 3 to the turbocharge system of the engine which is denoted 5. The turbocharge system feeds via an air cooler 7 a receiver 6, which again feeds scavenging and charging air to the engine. The turbocharge system 5 delivers the gas used by it to an outlet passage system 40.

In the embodiment of Fig . 3, an apparatus 80 is inserted between the receiver 3 and the outlet passage system, which apparatus serves to utilize the fraction of the exhaust gas by-passing the turbocharge system for secondary energy production, viz. in the form of a gas turbine coupled to a generator, the gas turbine being diagrammatically illustrated in Figs. 6 and 7. The input side of the gas turbine is connected to the exhaust gas receiver 3 by means of a tubular passage 41 which, as illustrated in Fig . 6, leads to the input side of the gas turbine there illustrated. The output side of the gas turbine is connected with the outlet passage system 40. Like in the case of the engine of Figs. 1 and 2, the outlet passage system 40 may be associated with a boiler 70, Fig . 3, e.g . a steam boiler with an input 71 and an output 72, or some other form of apparatus for utilizing the thermal energy of the exhaust gas. The boiler 70 in Fig . 3 may, like that in Fig . 1 , be disconnected by means of a throttle 75 in an exhaust conduit 76 opening into the atmosphere.

In principle the engine of Figs. 3 and 4 may be controlled in the same manner as explained in connection with Fig. 2, viz. by means of a throttle 9 mounted in the passage 41 , such as diagrammaticaily shown in Fig. 5. To the extent possible, the same reference characters have been used in Fig . 5 as in Fig . 2, and it will therefore be directly understood that at increasing intake temperature the lever 14 is moved in the direction of the arrow 31 , whereby the gas supply to the gas turbine is reduced, while the gas supply to the turbocharge system is increased , and the same result is obtained as above explained . When the lever 21 is moved against the direction of the arrow 35, the throttle 9 is moved in the closing direction and thereby the same compensation effect for dropping turbocharger efficiency is obtained as above explained. The engine of Figs . 3 and 4, too, may be provided with a passage 78, Fig . 3, with a throttle 79 mounted therein , which throttle is kept open when the turbocharge system is operating at its maximum efficiency, and is closed when the initial drop has taken place, and is re-opened only if the whole turbocharge system is renovated.

When on the other hand considering the turning of the lever 15 depending on the engine load , the conditions in Fig . 5 are opposite to those in Fig . 2, the lever 15 being turned in the direction of the arrow 33 a, which is opposite to the direction of the arrow 33 in Fig . 2, when the engine load is increased . Thereby the gas supply to the gas turbine 80 is decreased , and consequently the gas supply to the turbocharge system is increased. However, this control at increasing load is not extended beyond a point such that the permissible maximum pressure is not exceeded . At dropping load the control takes place in the opposite direction , but only down to the minimum load, where it is still possible to utilize the energy of the exhaust gas for secondary power production with any advantage and with due regard to the operating conditions of the engine as a whole, i . e. oil consumption and thermal load. Below this range, the exhaust gas supply for secondary power production is closed Off either completely or to the extent permissible with a view to the stability of the turbocharge system. Fig . 5 shows an additional lever 44 with shaft 45 interposed between the two levers 14 and 15, the lever 44 being connected with the levers 14 and 15 by means of rods 46 and 47, which are controlled in the same manner as explained in connection with Fig. 2, but not illustrated in detail in Fig. 5. The lever 44 is used when it is desired to control or adjust the supply of exhaust gas to the gas turbine, the lever 44 being in that case turned in the direction of the arrow 48. This control or adjustment takes place depending on the demand which may e. g. vary in the course of the 24 hours of the day, in the course of the year and depending on the climatic conditions . It will be seen that when the lever 44 is turned in the direction of the arrow 48, the throttle 9 will be moved in the opening direction so that more exhaust gas is supplied to the gas turbine.

In the foregoing the control as such has for simplicity been mentioned as taking place by means of a simple throttle 9. Fig . 6 shows a somewhat more detailed throttle arrangement. As previously mentioned , 80 denotes the gas turbine, and 41 the inlet of the latter. The inlet blade ring of the gas turbine is diagrammatically shown in Fig. 6 and denoted by 50. The inlet to the blade ring 50 is subdivided into three portions 51 , 52 and 53, and the admission to each biade ring portion is controlled by means of a throttle 54, 55, and 56, respectively. Moreover, the gas turbine may be constructed with a by-pass 57 which can be controlled by means of a throttle 58 and can be completely closed or opened by means of a throttle 59. By re-setting the throttle 59 from the position shown in Fig . 6 in the direction indicated by an arrow the inlet to the gas turbine is closed and the by-pass 57 is opened so that racing of the gas turbine, e. g . in the case of a sudden drop of the load of the generator operated by the gas turbine, can be avoided. The throttle 58 is then so adjusted that the free passage area of the by-pass 57 corresponds to the free passage area of the portions 51 , 52 and 53 at the time when the admission to these is closed by means of the throttle 59, so that the operating conditions of the engine are not changed. The throttles 54, 55 and 56 are ϊn principle used in the same manner as the throttle 9 in Fig. 5. The aim of using the three throttles in Fig. 6 is to obtain a good efficiency of the gas turbine 80 in the following manner: At the commencing shut-off of the supply of exhaust gas to the gas turbine, one throttle is first gradually closed, and then the second one and finally the third one so that the turbine maintains an acceptable efficiency during the progress of the control . The gas turbine may, if desired, be constructed with a controllable passage area and, if desired, at the same time with the subdivision referred to. The gas turbine 80 is, as shown in Fig . 7, coupled to a generator 60 of well known design . It will be understood, however, that ϊn cases where a different form of energy is desired, such as heat, the gas turbine with appurtenant generator may be replaced e. g . by a boiler. From the above explanations it will be understood that the turbocharge system 5 is in reality by-passed to the exhaust system after the turbine portion of the turbocharge system by means of a by-pass opening , and that the maximum area of the latter is advantageously related to the total efficiency of the turbocharge system employed, ϊn such a manner that the maximum utilized area of the by-pass opening is the greater, the higher the efficiency is, meaning that a higher by-passed amount and thereby a higher amount of energy are available for control , the higher the efficiency of the turbocharge system employed is. More specifically, the by-pass area can be put in relation to the ratio: η2 ηl . 100 η1 where η1 , roughly 60%, is the efficiency which has hitherto been con sidered the minimum efficiency acceptable on delivery of a new engine system, and η2 is the efficiency obtainable and commercially available at any particular moment. Typically, the maximum effective by-pass area used in practice during the control will be 1 to 2 times that mentioned above, expressed in percentage of the total equivalent or effective passage area of the turbocharge system in question , the higher factors being used in cases where the energy of the exhaust gas is used for energy production , and the lower factors where this is not the case.

To sum up , it is pointed out that according to the invention one obtains a lower average specific fuel oil consumption, a levellϊng- out of the thermal load of the engine, and an economic utilization of the heat content of the exhaust gas, and thereby a more profitable overall efficiency is obtained, viz. by the advantageous control of the by-pass area as above explained, the principle of which is that the size of the area is controlled within the upper range in temperate climate, and the higher up , the lower the intake temperature and/or the gas temperature are, and the higher the barometric level , the charging efficiency and the demand for exhaust energy are. Similarly, under tropical conditions the said favourable adjustments are obtained by choosing the size of the area in the lower range, and the lower, the higher the intake temperature and/or the gas temperature are, and the lower the barometric level, the charging efficiency and the demand for exhaust gas energy are.

Depending on the wish for more, respectively less exhaust gas energy at partial loads and with due regard to the conditions of operation of the engine, the size of the by-pass area is chosen higher, respectively lower at dropping loads in the range down to about 75% load . At partial loads below 75%, the by-pass area is always chosen the lower, the lower the load is.

Claims

P a t e n t C l a i m s:

1. Method for operating an internal combustion engine with turbocharge system, c h a r a c t e r i z e d in that a turbocharge system and an engine are used which are so constructed and dimensϊoned, and the turbocharge system has an efficiency so high, that at low air intake temperature the turbocharge system is capable of delivering the amount of air calculated or suitable for the engine at the pressure calculated or suitable for the engine when a fraction only of the exhaust gas delivered by the engine is fed to the turbocharge system, that at low air intake temperature a fraction only of the exhaust gas delivered by the engine is fed to the turbocharge system, that the remainder of the exhaust gas is conducted to the atmosphere in by-pass to the turbocharge system, and that the proportion between the fraction of the exhaust gas by-passing the turbocharge system and the fraction of the exhaust gas supplied to the turbocharge system is decreased at increasing air intake temperature and increased at decreasing air intake temperature.

2. Method according to claim 1, c h a r a c t e r i z e d in that the proportion between the fraction of the exhaust gas by-passed to the .atmosphere and the fraction supplied to the turbocharge system is increased upon overhauling of the turbocharge system.

3. Method according to claim 2, c h a r a c t e r i z e d in that the proportion between the fraction of the exhaust gas by-passed to the atmosphere and the proportion supplied to the turbocharge system is decreased by a predetermined limited amount during the progress of a certain time interval after the taking into use of the engine to compensate for the abatement of the air delivery conditions of the turbocharge system and its initial drop of efficiency.

4. Method according to claim 1, c h a r a c t e r i z e d in that the fraction of the exhaust gas by-passed to the atmosphere is utilized for the production of secondary energy.

5. Method according to claim 1, where the fraction of the exhaust gas by-passed to the atmosphere is not utilized for the production of secondary energy, c h a r a c t e r i z e d ϊn that the proportion between the fraction of the exhaust gas by-passed to the atmosphere and the fraction supplied to the turbocharge system is decreased at decreasing engine load.

6. Method according to claim 4, c h a r a c t e r i z e d in that the proportion between the fraction of the exhaust gas by-passed to the atmosphere and the fraction supplied to the turbocharge system is increased at increasing demand for the production of secondary energy.

7. Method according to claim 6, c h a r a c t e r i z e d in that the proportion between the fraction of the exhaust gas by-passed to the atmosphere and the fraction supplied to the turbocharge system is increased at decreasing load of the engine.

8. Internal combustion engine having a turbocharge system, c h a r a c t e r i z e d in that the turbocharge system and the engine are so constructed and dimensioned, and the turbocharge system has an efficiency so high, that at low air intake temperature the turbocharge system is capable of delivering the amount of air calculated or suitable for the engine at the pressure calculated or suitable for the engine when a fraction only of the exhaust gas deliver ed by the engine is fed to the turbocharge system through appurtenant feeding means (4), and the engine has means (11) for branching off the remaining fraction of the exhaust gas delivered by the engine (1) so that this fraction is passed to the atmosphere in by-pass to the turbocharge system, the engine being provided with control means (9) which are so arranged and actuable in such a manner that the proportion between the fraction of the exhaust gas caused to by-pass the turbocharge system through the branch-off means (11) and the fraction of the exhaust gases supplied to the turbocharge system through the feeding means is adapted to be decreased at increasing air intake temperature and to be increased at decreasing air intake temperature.

9. Internal combustion engine according to claim 8, c h ar a c t e r i z e d ϊn that the control means (9) are arranged to control the passage area of the branch-off means (11).

10. Internal combustion engine according to claim 9, c h ar a c t e r i z e d in that the control means comprise means (79) for permanently decreasing the maximum passage area of the branch-off means by an amount corresponding to the drop of the initial efficiency of the turbocharge system not regenerated later, and to the drop of air input normally taking place owing to changes of installation conditions from test run ϊn the workshop to the final operation of the completed system.

11. Internal combustion engine according to claim 10, c h a r a c t e r i z e d in that the means are constituted by a separate throttle (79) which is closed after a few months of operation and is not utilized later.

12. Internal combustion engine according to claim 9, and ϊn which the fraction of the exhaust gas by-passed to the atmosphere is not utilized for the production of secondary energy, c h a r a c t e r i z e d ϊn that the control means (9) are adapted to decrease the passage area of the branch-off means (11) at decreasing engine load, and to increase the passage area of the branch-off means at increasing engine load.

13. Internal combustion engine with turbocharge system according to claim 9 and ϊn which the branch-off means (41) are arranged to supply the branched-off fraction of the exhaust gas to an apparatus (80) for the production of secondary energy, c h a r a c t e r i ze d ϊn that the control means are arranged to increase the passage area of the branch-off means at increasing demand for secondary energy utilization and to decrease the passage area of the branch-off means at decreasing demand for secondary energy.

14. Internal combustion engine according to claim 13, where the apparatus for the production of secondary energy is a gas turbine (80), c h a r a c t e r i z e d in that the gas turbine is provided with two or more inlets (51, 52, 53) to separate turbine nozzle sections, and the control means are constituted by closable throttles (54, 55, 56) which are mounted ϊn the inlets (51, 52, 53), and at least one of which is controllable.

15. internal combustion engine according to claim 8, c h ar a c t e r i z e d in that the maximum free passage area of the branch-off means fulfils the following conditions:

where

A oml. is the maximum free passage area of the branch-off means, A tur. is the total equivalent or effective turbine passage area of the turbocharge system considered, η1 is the efficiency of the turbocharge system which has hitherto been considered the minimum efficiency hitherto considered satisfactory, and η2 is the efficiency of the turbocharge system at any time obtainable as a maximum and commercially available.